I have a friend who's got 4 rescue horses. Two are elderly, one is a mare who's "older than 30" she's been having problems going down to sleep and not being able to get up again because of an old shoulder injury. He's managed to get her a custom built Anderson sling type set up -- they're putting in the posts for it now. But all through the winter, she'd go down and he'd have to watch her so he could bring out his family (they're home-schoolers) to help get her back on her feet.

The poor old girl's mostly toothless, has a bad shoulder and was several hundred pounds underweight when rescued from the auction house 5 years ago. The horse rescue people he adopted her from 3 or so years ago hadn't done much with her -- basically left her in a paddock to die. To see her now is amazing. She's still a battered old beast, but no longer painfully thin and with a coat that gleams.

You might want to look into making a sling if Dusty starts to gave problems with going down. They're horribly pricey, but not impossible to make if you've got a sewing machine that'll handle canvas and the ability to build a frame for it.